Spectral index maps of the radio relic regions. Top panels: spectral index maps derived from the high-resolution image set (beam: 12″ × 12″). Bottom panels: spectral index maps derived from the low-resolution image set (beam: 26″ × 26″). Corresponding error maps are shown in Fig. B.1. In all panels, contours are taken from the flat-noise map at (7, 25, 60)×σ with σ = 6.3 μJy beam⁻¹ and beam 10″ × 10″.